Conventionally, a sliding bearing is known which is configured into a cylindrical shape with a pair of half-bearings placed abutting against each other, and provided with a chamfer part and a crush relief in an inner circumferential part of each of the abutting surfaces of the half-bearings (see FIG. 7). In such a sliding bearing provided with a crush relief as a notch, when a lubricant is supplied from an oil hole of a crank shaft as shown in FIG. 7, a foreign substance mixed in the lubricant is trapped by the crush relief and then discharged to the outside through the crush relief and openings on both sides of the chamfer part.
Conventionally, a sliding bearing is proposed in which a foreign substance discharging groove is formed at a required location of the sliding surface so as to trap and discharge the foreign substance mixed in the lubricant (e.g., Patent Literature 1 to Patent Literature 4).
In the sliding bearing of Patent Literature 1, an oil groove is provided over the entire area in the circumferential direction of the sliding surface of the lower half-bearing and a pair of foreign substance discharging grooves are formed which are branched from the oil groove and open to both end faces in the axial direction of the half-bearing.
Furthermore, the sliding bearing of Patent Literature 2 is configured such that the axis of rotation is axially supported by a plurality of arc-shaped pads, a T-shaped groove is formed on the sliding surface of each arc-shaped pad to trap a foreign substance and a magnet is set up at the bottom of the axial direction groove in the T-shaped groove. The magnet is intended to attract and trap the foreign substance in the axial direction groove.
Furthermore, in the sliding bearing of Patent Literature 3, a plurality of rectilinear foreign substance discharging grooves are formed along the axial direction in the vicinity of the abutting surface of the lower half-bearing.
Furthermore, in the sliding bearing of Patent Literature 4, an axial direction groove having a triangular cross section is provided at an inner edge of the abutting surface of the half-bearing and a circumferential direction groove is formed adjacent to the axial direction groove within a predetermined range of the sliding surface.